World Air Quality Index sensor (#4434)

* Implement WAQI sensor

* Corrections based on CI check.

* Updated requirements_all.txt for pwaqi==1.2

* Require latest version of pwaqi

* Fix lint: single argument for .exception and no more pass statement.

* Further lint fixes.

* pydocstyle fix

* Implement rate throttle.
Data on WAQI is usually updated once an hour - make it refresh every thirty minutes.

* Implement schema validation with voluptuous.
Change exception handling scope.
Move messages to debug().

* Fix lint (empty indented line).

* Sort lines correctly.

* Fix last lint issue.

* Provide additional sensor data as received from WAQI.
Easier-to-read throttle timing.

* Additional object attributes to be unrolled later.

.coveragerc

@@ -308,6 +308,7 @@ omit =
     homeassistant/components/sensor/twitch.py
     homeassistant/components/sensor/uber.py
     homeassistant/components/sensor/vasttrafik.py
+    homeassistant/components/sensor/waqi.py
     homeassistant/components/sensor/xbox_live.py
     homeassistant/components/sensor/yweather.py
     homeassistant/components/switch/acer_projector.py

homeassistant/components/sensor/waqi.py

@@ -0,0 +1,97 @@
+"""
+Support for the World Air Quality Index service.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.waqi/
+"""
+import logging
+from datetime import timedelta
+from homeassistant.helpers.entity import Entity
+from homeassistant.util import Throttle
+from homeassistant.helpers.config_validation import PLATFORM_SCHEMA
+from homeassistant.helpers import config_validation as cv
+import voluptuous as vol
+
+REQUIREMENTS = ["pwaqi==1.2"]
+
+_LOGGER = logging.getLogger(__name__)
+
+SENSOR_TYPES = {
+    'aqi':          ['AQI', '0-300+', 'mdi:cloud']
+}
+
+ATTR_LOCATION = 'locations'
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Required(ATTR_LOCATION): cv.ensure_list
+})
+
+# Return cached results if last scan was less then this time ago
+MIN_TIME_BETWEEN_UPDATES = timedelta(minutes=30)
+
+
+def setup_platform(hass, config, add_devices, discovery_info=None):
+    """Setup the requested World Air Quality Index locations."""
+    dev = []
+    import pwaqi
+    # Iterate each module
+    for location_name in config[ATTR_LOCATION]:
+        _LOGGER.debug('Adding location %s', location_name)
+        station_ids = pwaqi.findStationCodesByCity(location_name)
+        _LOGGER.debug('I got the following stations: %s', station_ids)
+        for station in station_ids:
+            dev.append(WaqiSensor(station))
+
+    add_devices(dev)
+
+
+# pylint: disable=too-few-public-methods
+class WaqiSensor(Entity):
+    """Implementation of a WAQI sensor."""
+
+    def __init__(self, station_id):
+        """Initialize the sensor."""
+        self._station_id = station_id
+        self._state = None
+        self.update()
+
+    @property
+    def name(self):
+        """Return the name of the sensor."""
+        if 'city' in self._data:
+            return "WAQI {}".format(self._data['city']['name'])
+        return "WAQI {}".format(self._station_id)
+
+    @property
+    def icon(self):
+        """Icon to use in the frontend, if any."""
+        return "mdi:cloud"
+
+    @property
+    def state(self):
+        """Return the state of the device."""
+        return self._state
+
+    @property
+    def unit_of_measurement(self):
+        """Return the unit of measurement of this entity, if any."""
+        return "AQI"
+
+    @property
+    def state_attributes(self):
+        """Return the state attributes of the last update."""
+        return {
+            "time": self._data.get('time', 'no data'),
+            "dominentpol": self._data.get('dominentpol', 'no data')
+        }
+
+    @Throttle(MIN_TIME_BETWEEN_UPDATES)
+    def update(self):
+        """Get the data from World Air Quality Index and updates the states."""
+        import pwaqi
+        try:
+            self._data = pwaqi.getStationObservation(self._station_id)
+
+            self._state = self._data.get('aqi', 'no data')
+        except KeyError:
+            _LOGGER.exception('Unable to fetch data from WAQI.')

requirements_all.txt

@@ -330,6 +330,9 @@ pushbullet.py==0.10.0
 # homeassistant.components.notify.pushetta
 pushetta==1.0.15
 
+# homeassistant.components.sensor.waqi
+pwaqi==1.2
+
 # homeassistant.components.sensor.cpuspeed
 py-cpuinfo==0.2.3